TRIGON IA angulata. 
TAB. DVIII.—fg. 1. 
Spec. Cuar. Transversely elongated, convex ; pos- 
terior side produced, truncated, transversely 
striated, bounded by a crenulated line ; the 
remainder ornamented with nodose ridges bent 
at right angles as they pass over the middle. 
Syn. Trigonia clavellata var. Min. Conch. t. 8%. 
lower figures. Vol. 1. p. 197. 
8 
Upon the posterior side are not only transverse strie, 
but there is generally a crenulated ridge in the middle 
of it; the crenulations upon this and also upon the 
bounding lines are often elevated into small spines. The 
curvature, like the letter S, of the concentric ridges,which 
are sometimes divided into distinct tubercles, and at 
other times continuous, is a strong and constant charac- 
ter. The portion above the anterior side (correspond- 
ing with the lunette in other shells, but very large in this) 
is smooth. The breadth seldom exceeds an inch and a 
half. 
An excellent specimen lately lent us by our good 
friend ‘Thomas Meade, Esq. has shown this to be a dis- 
tinct species, which the imperfect specimens formerly - 
figured were not sufficient for. It is from Brewham near 
Nunney. The accompanying shells are Astarte elegans 
(M. C. 137.), an unpublished one, resembling a Tellina, 
and, at the back of the mass, fragments of a smooth 
Pecten. 
